U.S. patent number 5,494,121 [Application Number 08/346,089] was granted by the patent office on 1996-02-27 for cavern well completion method and apparatus.
Invention is credited to Alan L. Nackerud.
United States Patent |
5,494,121 |
Nackerud |
February 27, 1996 |
Cavern well completion method and apparatus
Abstract
A method and apparatus for increasing the diameter of a well
bore in a cavern well completion after a drill pipe has been
removed from the well bore and a drill bit has been removed from
the drill pipe in which a reaming tool is formed with one or more
cutters of a length in excess of the radius of the previous well
bore, the cutters being attached by a pin to a coupling at the
lower end of the drill pipe, the cutters being in the form of flat
cutter blades which are capable of moving from overlapping relation
to one another into diametrically opposed perpendicular relation to
the rotational axis of the drill pipe and coupling when the drill
pipe is rotated. The rotating drill pipe can be raised or lowered
to lengthen the enlarged well bore to form an increased surface
area of pressurized formation which is open to communicate with the
less pressurized interior of the well bore and thereby
substantially increase production flow rates.
Inventors: |
Nackerud; Alan L. (Littleton,
CO) |
Family
ID: |
22882977 |
Appl.
No.: |
08/346,089 |
Filed: |
November 29, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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234823 |
Apr 28, 1994 |
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Current U.S.
Class: |
175/263 |
Current CPC
Class: |
E21B
10/32 (20130101) |
Current International
Class: |
E21B
10/26 (20060101); E21B 10/32 (20060101); E21B
010/00 () |
Field of
Search: |
;175/57,263,265,273,275,277 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Buiz; Michael Powell
Attorney, Agent or Firm: Reilly; John E.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation-in-part application of Ser. No. 234,823,
filed 28 Apr., 1994 entitled CAVERN WELL COMPLETION by Alan L.
Nackerud, now abandoned.
Claims
I claim:
1. In apparatus for enlarging earth bores wherein rotational energy
means is lowered through an earth bore to a position at which it is
desired to enlarge the diameter of said bore, the improvement
comprising:
a reaming tool including a coupling member connectable to a lower
end of said rotational energy means;
a plurality of elongated cutter blades each in the form of a flat,
rigid arm member having outside edge means along opposite elongated
edges of said cutter blade and opposed, substantially flat parallel
surfaces between said outside edge means; and
pivotal cutter means for pivotally connecting an upper end of each
of said cutters to said coupling with said parallel surfaces
parallel to one another whereby activating said rotational energy
means will cause said cutter blades to pivot in opposite directions
away from overlapping relation to one another into positions
perpendicular to said bore whereby said cutter arms substantially
enlarge the diameter of said bore.
2. In apparatus according to claim 1, said reaming tool including
means between said coupling and said cutter arms to restrict said
cutter arms from rising beyond the perpendicular position.
3. In apparatus according to claim 1, wherein said reaming tool
includes means between said coupling means and said cutter arms to
cause said cutter arms to pivot in opposite direction into
positions substantially perpendicular to said bore.
4. In apparatus according to claim 1, said pivotal connecting means
defined by a common pin member extending transversely through upper
ends of said cutter arms.
5. In apparatus according to claim 1, said cutter blades including
cuttings hole means extending substantially transversely through
each of said cutter blades at uniformly spaced intervals along the
lengths of said cutter arms.
6. In apparatus according to claim 1, wherein means are provided
for pumping air or drilling mud downwardly through said bore for
lifting formation cuttings from said enlarged diameter of said bore
to the surface.
7. In apparatus according to claim 6, wherein circulation means are
provided on said cutter blades for delivery of air or drilling mud
into the formation.
8. In apparatus for enlarging earth bores wherein rotational energy
means is lowered through an earth bore to a position at which it is
desired to enlarge the diameter of said bore, the improvement
comprising:
a reaming tool including a coupling member connectable to a lower
end of said rotational energy means;
a plurality of elongated cutter blades each in the form of a flat,
rigid arm member having outside edge means along opposite elongated
edges of said cutter blade and opposed, substantially flat parallel
surfaces between said outside edge means; and
pivotal cutter means in the form of a pin for pivotally connecting
an upper end of each of said cutters to said coupling with said
parallel surfaces parallel to one another with said cutter blades
disposed on opposite sides of a rotational axis through said
coupling member whereby activating said rotational energy means
will cause said cutter blades to pivot in opposite directions away
from overlapping relation to one another into positions
perpendicular to said bore whereby said cutter arms substantially
enlarge the diameter of said bore.
9. In apparatus according to claim 8, wherein said pin traverses a
slot portion in which the upper ends of said cutter blades are
mounted.
10. In apparatus according to claim 8, said cutter blades including
cuttings hole means at spaced intervals along the length
thereof.
11. A method for substantially increasing the diameter of a well
bore in a cavern well completion after a hollow drill pipe has been
pulled out of the well bore and a drill bit has been removed from
the drill pipe, the improvement comprising the steps of:
attaching at least one pivotal cutter means to the drill pipe, said
pivotal cutter means having outside sharpened edge means
alternately angled in and out along its outside length;
providing a coupling means which connects the pivotal cutter means
to a rotational energy means;
lowering the pivotal cutter means to a position in an uncased
portion of the well bore; and
rotating the drill pipe and the pivotal cutter means so that a
rotational force causes the pivotal cutter means to cut into the
formation and rotate to a position perpendicular to the drill pipe
whereby said cutter means substantially enlarges the diameter of
the well bore.
12. The method of claim 11, further comprising the step of
substantially lengthening said enlarged well bore by moving said
rotational energy means up or down while rotating the cutter
means.
13. The method of claim 11, wherein said cutter means has a
plurality of cuttings holes means whereby formation cuttings pass
through the cutter means.
14. The method of claim 11, further comprising the step of:
attaching circulation pipe means to each of the cutter means
whereby a drilling mud or air can pass through said rotational
energy means, said coupling means and said circulation pipe means
in the removal of formation cuttings from said cavern.
15. The method of claim 14, further comprising the step of:
locating circulation port means along the length of the circulation
pipe means.
16. The method of claim 11, further comprising the step of
providing said coupling means with coupling slot means to permit
said cutter means to pivot in opposite directions, unobstructed by
said coupling means, to a position perpendicular to said rotational
energy means.
17. A method for substantially increasing the diameter of a well
bore in a cavern well completion after a hollow drill pipe has been
pulled out of the wellbore and a drill bit has been removed from
the drill pipe, the improvement comprising the steps of:
attaching at least one pivotal cutter means to the drill pipe, said
pivotal cutter means having a plurality of cuttings hole means and
an outside sharpened edge means alternatively angled in and out
along its outside length, said pivotal cutter means further has a
top radial cut corner means to allow the cutter means to pivot in
only one direction to a position perpendicular to a rotational
energy means, and another top side corner is a ninety degree corner
means which restricts the pivotal cutter means from rising further
than the perpendicular position;
providing a coupling means which connects the pivotal cutter means
to said rotational energy means;
lowering the pivotal cutter means to a position in an uncased
portion of the well bore;
rotating the drill pipe and the pivotal cutter means so that a
rotational force causes the pivotal cutter means to cut the
formation and rotate to a position perpendicular to the drill pipe
whereby the cutter means substantially enlarge the diameter of the
well bore; and
pumping air or drilling mud down the interior of the hollow drill
pipe and lifting the formation cuttings between the drill pipe and
casing to the surface.
Description
BACKGROUND OF THE INVENTION
This invention relates to method and apparatus for reaming or
enlarging earth bore diameters; and more particularly relates to a
novel and improved method and apparatus for cutting through a
productive downhole formation to form a well bore diameter
substantially larger than a conventionally drilled well bore in
order to increase production rates.
In the recovery of petroleum or other gas or liquid substances from
subterranean formations, a well bore is formed into the earth and
into or beyond the producing formation. A productive well bore is
then "completed" either by conventional "cased hole" or "open hole"
completion.
In conventional cased hole completion, the casing is run into the
completed well bore through and beyond the productive formation
after which the casing is cemented in place and then perforated to
provide communication between the producing formation and the
interior of the casing. Conventional perforations form holes in the
casing approximately 3/8" in diameter and the perforation
projectile travels a distance of a few inches to a few feet into
the formation. Conventional wells typically have one or more
perforations per foot.
In conventional open hole completion, the well bore is drilled into
the top portion of the productive formation and casing is run to
the top of the productive formation and cemented in place. The well
bore is then deepened through the productive formation and left
open to communicate with the interior of the well bore. Generally,
this method establishes more communication with the well bore than
a conventional cased hole. The types of completion described are
somewhat effective in formations with high permeability. However,
with the recent increased number of well completions in formations
having low permeability, low production flow rates have resulted
with long economic payout periods and unsatisfactory rates of
return on investment. The reserves in place may be substantial, but
the production flow rates are usually unsatisfactory. The
conventional types of completion described provide insufficient
productive formation surface area open to communicate with the well
bore. Many of the producing formations of these wells are several
feet to several hundred feet thick and friable yet structurally
strong enough not to collapse when open hole completed.
In the past, many conventional well completions have included
various flow rate enhancement treatments including chemical
treatments, fracture proppant treatments, horizontal drilling and
combinations thereof. Nevertheless, conventional open hole and
cased hole completions and subsequent treatments have suffered from
numerous drawbacks including:
(a) the surface area of productive formation open to communicate
with the interior of the well bore is marginal;
(b) the introduction of foreign treatment chemicals to the
formation often chemically alters the formation, activating clays
and other flow restricting minerals;
(c) the proppants often break down from formation pressure and
create fines which restricts production flow;
(d) the proppant fracture treatments fill the well bore with
unwanted proppant precluding installation of downhole production
equipment. An expensive workover rig capable of removing the
proppant out of the well bore must be employed;
(e) the polymer gels used to assist the proppant into the induced
fractures do not entirely break down to a retrievable fluid which
restricts production flow;
(f) the chemical or proppant treatments are not controllable as to
where they propagate. Neighboring zones containing unwanted
production such as salt water are often fractured into and then the
unwanted production cannot be stopped;
(g) the chemical and/or proppant may be placed in the induced
fractures and yet be squeezed off at any point in the fracture area
and especially near the well bore making the proppant
ineffective;
(h) the desired production becomes mixed and contaminated with the
foreign treatment liquids, gases or solids and are expensive to
extract;
(i) the contaminated production postpones initial production
revenues;
(j) the contaminated gas production is often vented to atmosphere
and contaminated liquid production often incorrectly disposed of
causing environmental contamination;
(k) the mixing of treatment chemicals with formation solids,
liquids and gases often forms corrosives that corrode production
equipment and pipelines;
(l) the horizontal drilling requires an expensive and complicated
downhole directional drilling tool and still provides only a
marginal increase in the productive formation surface area open to
communicate with the well bore;
(m) the chemicals and acids used are a human health hazard and when
not properly handled cause serious accidents;
(n) the foreign treatment proppants cause scoring damage and
blockage to pumping equipment;
(o) the chemical and proppant fracture treatments require
additional equipment, such as, frac tanks, sand and/or chemical
trucks, and pumping trucks which cause additional damage to the
landowner's surface;
(p) the oil and natural gas purchasers and pipeline companies will
not allow numerous fracture treatment gases and liquids in the
production because it lowers its heating value; and
(q) the initial flow rate tests are inaccurate due to flow back of
treatment fluids and treatment gases.
It is therefore desirable to provide for a method and apparatus for
substantially increasing the surface area of the productive
formation in such a way as to result in substantially increased
production rates and to overcome the numerous problems and
drawbacks inherent in conventional open hole and cased hole
completions as well as subsequent enhancement treatments. In
particular, it is proposed to employ a novel and improved reaming
device for enlarging a well bore diameter at the productive
formation which is characterized by its ease of installation,
operation, versatility and reliability in use.
Representative reaming tools are disclosed in U.S. Pat. Nos. 54,144
to Hamar, 639,036 to Heald, 1,189,560 to Gondos, 1,285,347 to Otto,
1,467,480 to Hogue and 1,485,615 to Jones. Although these devices
generally disclose the concept of utilizing one or more pivotal
cutters which will swing outwardly under centrifugal force into
cutting engagement with the sides of a hole, they are lacking in
any suggestion of utilizing flat rigid cutter blades which are
capable of swinging outwardly from a position in which the blades
are disposed in overlapping relation to one another to a
perpendicular position to the rotational axis and which will afford
adequate relief for the removal of formation cuttings as the cutter
blades are rotated.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide for a
novel and improved well completion method and apparatus which will
substantially increase the surface area of a pressurized productive
formation which is enlarged to communicate with the existing well
bore so that increased production rates can be obtained and to do
so without formation damage caused by chemical alteration of the
formation, or without flow restrictions caused by proppant
breakdown tending to release unwanted small particles, or without
residual sand in the well bore or residual gels in the formation
and will not propagate to neighboring formations containing
unwanted production.
It is another object of the present invention to provide for a
novel and improved well completion method and apparatus for
increasing the surface area of a productive formation in
communication with a lesser pressurized interior of a well bore
which cannot be squeezed off and become ineffective, does not
require extraction of treatment materials from production, and
avoids contaminated production as well as avoiding the use of
complicated downhole equipment while minimizing pipeline and
production equipment corrosion.
It is a further object of the present invention to provide for a
novel and improved method and apparatus for well completion of the
type described which does not require acids or chemicals hazardous
to human and environmental health, avoids proppant scoring and
blockage of pumping equipment and which can be carried out without
extraneous treating equipment to cause excess land surface damage,
avoids lowering of the heating value of the production and
minimizes erroneous flow test results.
It is a still further object of the present invention to provide
for novel and improved forms of reaming devices for use in
combination with a drill pipe or other rotational energy means for
enlarging a well bore diameter which are of simplified
construction, easy to install, compact, and highly efficient and
reliable in use.
In accordance with the present invention, a reaming tool has been
devised for use in combination with a drill pipe or other rotatable
energy means for enlarging the diameter of a well bore, the reaming
tool including a coupling member connectable to a lower end of the
rotational energy means, a plurality of elongated cutter blades
each in the form of a flat, rigid arm member having outside edge
means along opposite elongated edges of the cutter blade and
opposed, substantially flat parallel surfaces between the outside
edge means, and pivotal cutter means for pivotally connecting an
upper end of each of the cutter blades to the coupling such that
the parallel surfaces are disposed in parallel to one another and
activation of the rotational energy means will cause the cutter
blades to pivot in opposite directions away from overlapping
relation to one another into a position perpendicular to the
bore.
A method in accordance with the present invention for substantially
increasing the diameter of a well bore in a cavern well completion
after a hollow drill pipe has been pulled out of the well bore and
a drill bit has been removed from the drill pipe comprises the
steps of attaching at least one pivotal cutter means to the drill
pipe, the pivotal cutter means having a plurality of cuttings hole
means and an outside sharpened edge means alternately angled in and
out along its outside length, a pivotal cutter means being pivotal
in one direction to a position perpendicular to the rotational
energy means and being restricted from rising further than the
perpendicular position, and providing a coupling means which
connects the pivotal cutter means to the rotational energy means,
lowering the pivotal cutter means to a position in an uncased
portion of the well bore, rotating the drill pipe and pivotal
cutter means so that a rotational force causes the pivotal cutter
means to cut the formation and rotate to a position perpendicular
to the drill pipe whereby the cutter means substantially enlarges
the diameter of the well bore, and pumping air or drilling mud down
the interior of the hollow drill pipe and lifting the formation
cuttings between the drill pipe and casing to the surface.
The above and other objects of the present invention will become
more readily appreciated and understood from a consideration of the
following detailed description of preferred and modified forms of
the present invention when taken together with the accompanying
drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view in perspective of one form of reaming device
in accordance with the present invention;
FIG. 2 is a side view in perspective of the reaming device shown in
FIG. 1;
FIG. 3 is a somewhat schematic view of the form of invention shown
in FIGS. 1 and 2 in its assembled, rotating position within a well
bore;
FIG. 4 is another schematic view of the form of invention shown in
FIGS. 1 and 2 in a rotating position at the completion of a well
bore enlargement operation;
FIG. 5 is another front view in perspective of a modified form of
reaming device in accordance with the present invention;
FIG. 6 is a side view in perspective of the form of invention shown
in FIG. 4;
FIG. 7 is a somewhat schematic view of the form of invention shown
in FIGS. 5 and 6 in an assembled rotating position within a well
bore; and
FIG. 8 is a somewhat schematic view of the form of invention shown
in FIGS. 5 and 6 at the completion of a well bore enlargement
operation.
DETAILED DESCRIPTION OF FORM OF INVENTION SHOWN IN FIGS. 1 TO 4
Referring in more detail to FIGS. 1 to 4, there is illustrated one
form of reaming device 9 having a hollow coupling 11 adapted to be
attached to the lower end of a hollow drill pipe 10 or other
rotational energy means and a plurality of elongated cutters 15
pivotally connected to the lower end of the coupling by a common
attaching element in the form of a pin 13 extending through aligned
openings near the bottom of the coupling and is held in place by a
washer 22 and a nut 12. When the drill pipe 10 is rotated through
the force applied by a conventional drilling rig rotary table, the
cutter members 15 are urged under centrifugal force in opposite
directions away from a normally vertical orientation into a
substantially horizontal orientation perpendicular to the
rotational axis through the coupling, as best seen from FIGS. 3 and
4.
Each of the cutters 15 is in the form of a substantially flat,
rigid plate or blade having opposed, broad flat surface portions 24
and 25 in parallel to one another throughout its length and
alternately angled or serrated cutting edge portions 26 along
opposite edges for the substantial length of the blade. A
circulation pipe 16 of generally semi-circular cross-section is
affixed to one of the opposed, flat surface portions 24 having a
series of circulation ports 17 directed toward the outside edge of
each cutter 15, the pipe 16 extending the substantial length of the
cutter 15. Cuttings holes 18 are arranged at uniformly spaced
intervals along the length of each cutter 15 to permit formation
cuttings to pass through the holes 18 with minimum resistance.
In order not to interfere with pivotal movement of the cutters 15,
the upper end of each cutter has a radial corner 28, the corner 28
on one cutter being formed at an opposite edge opposite to the
radial corner 28 of the other cutter. The cutters 15 are suspended
by the pin member 13 which extends through a coupling slot 14 at
the lower end of the coupling 11, the coupling slot 14 being cut on
opposing sides on the bottom of the coupling to allow each cutter
15 to rotate in an opposite direction to a position perpendicular
to the drill pipe 10 under the application of rotational force.
When the drill pipe is not rotated and the cutters 15 are
vertically oriented, as shown in FIG. 1, the flat surface portions
of the respective cutters are in direct confronting and overlapping
relation to one another and, under rotation of the drill pipe, will
rotate away from one another into the perpendicular orientation
shown in FIGS. 3 and 4.
In operation, the well is drilled to the top of the producing
formation in accordance with conventional practice, and a cement
layer 19 is placed between a casing 20 and a well bore 21 and
allowed to harden. The well bore 21 is then deepened through the
producing formation. The drill pipe 10 is withdrawn from the well
bore 21 and the conventional drill bit removed. The reaming device
9 is attached to the bottom of the drill pipe 10 and lowered to a
position in the uncased portion of the well bore 21. When the drill
pipe 10 is rotated by the conventional drilling rig rotary table,
the centrifugal force applied to the reaming device 9 will cause
the cutters 15 to spread or pivot outwardly as described to cut
through the formation and gradually rotate into a position
perpendicular to the drill pipe 10, as shown in FIGS. 3 and 4, to
substantially enlarge the diameter of the well bore 21. Air or
drilling mud is then pumped down the interior of the hollow drill
pipe 10 and hollow coupling 11 through the circulation pipes 16 to
lift the formation cuttings between the drill pipe 10 and casing 20
to the surface.
The desired height of the enlarged diameter well bore or cavern is
completed by raising and lowering the drill pipe 10. As shown in
FIG. 4, the drill pipe is continuously rotated until the cutters 15
form a cavern in which the top side is perpendicular to the drill
pipe 10; or, in the alternative, a sloped top side could be cut
with a slower rotational speed of the drill pipe 10. The cutter
arms 15 have lengths equal to the radius of the desired cavern, or
shorter length cutters may be employed in the event that the well
bore 21 is to be progressively enlarged due to formation
characteristics or available rotational force. Most desirably, the
cutters 15 have a length equal to or slightly less than the
thickness of the formation; and by cutting an enlarged diameter
well bore through the producing formation, the production flow rate
is substantially increased by increasing the surface area of the
pressurized reservoir formation open to communicate with the
interior of the less pressurized cased well bore 21.
DETAILED DESCRIPTION OF FIGS. 5 to 8
In the modified form of invention shown in FIGS. 5 to 8, like parts
to those of FIGS. 1 to 4 are correspondingly enumerated with prime
numerals. As in the form of FIGS. 1 to 4, a reaming device 9'
includes a hollow coupling 11' having an upper threaded end portion
for threaded connection to the lower end of a drill pipe 10'. A
pair of cutter arms 15' are pivotally connected within a slotted
portion 14' at the lower end of the coupling 11' by a single pin
13'.
Each of the cutter arms 15' is in the form of an elongated flat
plate member having a length corresponding to the desired radial
length of the enlarged cavern to be formed out of the well bore
21'. Further, each cutter arm 15' has opposed, flat parallel
surface portions 24' and 25' with alternately angled or serrated
portions 26' along opposite side edges, and cuttings holes 18' are
formed in each cutter arm 15' at uniformly spaced intervals for
passage of formation cuttings therethrough. The slotted portion 14'
has side openings 30' in diametrically opposed sidewall portions of
the lower end of the coupling 11' aligned with upper ends of the
cutter arms 15' to permit outward pivotal movement of the cutter
arms 15' in opposite directions away from the coupling when rotated
by the drill pipe 10'. In that the cutters 15' are mounted on a
common pin 13' with the rotational axis through the coupling
extending between the cutters 15' the cutters 15' will pivot in
opposite directions to one another through the diametrically
opposed side openings 30' and not require any form of restraint as
described in connection with FIGS. 1 to 4. Further, to this end, an
upper terminal edge 28' of each cutter arm 15' is of rounded or
generally semi-circular configuration so as not to interfere with
outward pivotal movement of each respective cutter 15' through the
slotted portion 14'; and the cutters are restricted from rotating
beyond a perpendicular orientation to the drill pipe 10' by the top
edge of the slotted portion 14'.
The serrations 26' on one cutter arm may be staggered with respect
to the serrations 26' of the other cutter arm, as a result of which
the lower distal or free end 32 is given a relatively blunt edge
compared to the sharper edge 34 of the other cutter so that the
length and weight of the cutters 15' are substantially the same.
For practical purposes, the cutter arms 15' can be of corresponding
configuration and size without staggering the serrated edges 26'.
More importantly, the flat parallel surface portions of the cutter
arms enable the cutter arms 15' to be superimposed with the flat
surface portions 24' and 25' of each in confronting relation to one
another so that the width of each cutting arm can correspond to the
substantial diameter of the drill pipe 10' for maximum strength and
rigidity. By forming cutting edges along both sides of each cutter
arm 15', the cutter arms 15' are capable of cutting or reaming both
when the drill pipe is raised and lowered as it is rotated.
It will be evident from the foregoing that the method and apparatus
of the present invention can be used on open hole wells or on old
wells already cased where the casing and cement across the zone may
be cut away by conventional methods to allow the reaming tool to be
utilized. In addition, the cutters, coupling and pin may be
composed of various high strength materials which will lend
sufficient strength and rigidity both to the mounting and cutting
force of the cutter arms, and the enlarged well bore itself can be
cut in various stages of increasing size by modifying the precise
configuration of the cutter arms as well as to vary the speed of
rotation of the drill pipe. The coupling and pin could be a
ball-and-socket or other retention and pivot means to secure the
cutter arms in place yet permit their pivotal movement as
described, although a particular advantage is the ability to use a
single high strength pin for suspension of both cutter arms from
the coupling as opposed to multiple pin members which would tend to
reduce the strength of the coupling and pins.
It is therefore to be understood that while different forms of
invention are herein set forth, the above and other modifications
and changes may be made in the construction of parts and sequence
of steps without departing from the spirit and scope of the present
invention as defined by the appended claims and reasonable
equivalents thereof.
* * * * *